PALM BEACH GARDENS, Fla. — Rory McIlroy took a three-stroke lead to the seventh tee in Sunday's final round of the Honda Classic and seemed in total control to finish off a wire-to-wire tour de force.

Then the Champions Course at the PGA National Resort and Spa took over. And McIlroy's wheels, along with many others atop the leaderboard, began to fall off. Carnage became the buzz word instead of birdie, crippling balls into water hazards became the norm.

At the end of all the wreckage, however, in the sun's fleeting light, Russell Henley sunk a three-foot birdie putt on the first extra hole to win a four-man playoff for his second PGA Tour title.

Henley, who started the day two-shots behind McIlroy, shot 2-over-par 72 to finish at 8 under for the tournament. He then beat McIlroy (74), Ryan Palmer (69) and Russell Knox (71), who all made par in the playoff on the 18th hole.

Henley, 24, who won the first full-field event in 2013 in the Sony Open, joined McIlroy, Harris English and Patrick Reed as the only players under 25 with multiple Tour titles.

"So much can happen on these last couple holes, and you know, that's been my thing this week. My attitude has been great. I haven't been hitting it perfect. A couple times I've hit in some funky spots and I've managed to clean it up nice and get up and down," Henley said. "I told (caddie Adam Hayes), no matter what, I'm going to hang in there the best I can, make good golf swings and I've got nothing to lose playing against these guys.

"So this is kind of out of nowhere how I've been playing lately and I just really tried to soak up the day and everything I could take out of it."

Henley looked to be done after making a double-bogey on the 15th. But then the other leaders started to make mistakes, most notably McIlroy, who was looking for his first Tour title in 18 months. He made five bogeys and a double-bogey on the 16th hole to fall back to the pack. He could have won the tournament if his 11-foot eagle putt on the 72nd hole would have fallen, but he made a two-putt birdie to get into the playoff.

"A 74 wasn't good enough to get the job done," said McIlroy, who took command with a 63 in the first round but became the first 54-hole leader to lose in the last six Hondas. "When you have a two-shot lead you have to go out and play well. The three-putt on 13 wasn't that bad but then I started hitting loose shots. Now I have to pick myself up and get back at it."

McIlroy, who is no longer frustrated with his new equipment and doesn't have to answer questions about endorsements, nonetheless recorded his seventh top-10 in his last 10 starts, including a win in the Australian Open.

Palmer looked to be in position for his first win in four years but made bogeys on two of his final three holes, including missing a four-foot par putt on the 72nd hole. Knox made a double-bogey on the 14th hole.

"If you told me 8 under was in a playoff, I would have said B.S.," Palmer said. "I was thinking 11, 12, and as the day went on, I thought, OK, maybe 10. But this game's hard, and you can see when it becomes crunch time under pressure, things happen."

Things happened to world No. 1 Tiger Woods — to his back. Woods, who fired his season-best 65 on Saturday, but pulled out after 13 holes Sunday due to lower back spasms. His title defense of this week's World Golf Championships-Cadillac Championship could be in jeopardy.